Funds are requested to upgrade an existing single crystal P4 X-ray diffractometer with a new generation CCD detector. This instrument will directly and immediately impact several NIH funded programs by facilitating characterization of key molecules or materials central to programs in antiviral agent development, radiopharmaceutical agent development, pharmaceutical synthesis via organometallic reagents, environmentally benign catalysis and processing, and crystal engineering. Critical structural information on large complex cluster compounds (polyoxometalates) with potent antivira1 activity (HIV, hepatitis B, respiratory syncytial virus, and influenza) and "green" processing can only be acquired through such instrumentation. The new technology recently introduced to crystallography by the coupling of a CCD detector to phosphors tuned to molybdenum and copper radiation affords data of quality far superior to the 1970's technology that we currently use. It will allow us to obtain better quality data with a reliable sealed tube source. Molybdenum radiation is essential for analysis of highly absorbing metal clusters and compounds that are prevalent in much of the synthetic chemical research conducted in the Chemistry Department and Department of Radiology at Emory University. The CCD detector will make data collection more rapid, allowing us to trot crystallography as a routine, but highly accurate, structural tool for synthetic chemists. A Staff Crystallographer has been hired using internal resources to manage the facility and provide structural data for a diverse group of synthetic inorganic, organometallic, organic, and pharmaceutical chemists. In summary- the requested upgrade will greatly enhance not only the productivity but also the quality of science of a diverse group of researchers in the Chemistry Department and School of Medicine at Emory University.